In the treatment of skin wherein an aqueous paste is applied to the skin, left in contact therewith for a period of time and thereafter removed, the improvement which comprises placing over the paste a foil containing at least about 3 percent of water soluble collagen by weight and having a water permeability of more than about 0.1 gram/dm2/minute, whereby collagen is transported through the paste and is absorbed by the skin. Desirably the foil is about 0.01 to 0.03 mm thick and is cross-linked to an extent corresponding to that produced by about 0.1-0.5 percent by weight of glutardialdehyde applied in an acid medium. It may further contain a cosmetically active agent such as an amino acid, peptide, protein, hormone, placenta-extract, phosphatide, tissue-extract, fresh cells and vitamins. The paste may be dried by heating, producing shrinkage of the foil to increase contact with the skin.